Intraspinal opiod and alpha-adrenergic agonist injection relieves both acute and chronic pain and may decrease postoperative morbidity and mortality. However, bothersome or dangerous side effects from these drugs limit widespread use. This application examines a novel approach to providing spinal analgesia with fewer side effects. Neostigmine is already approved for use by injection into the vein but this is the first human study of its use in the spinal space. Safety and effects on pain threshold of spinal neostigmine will be assessed.